casatasks

Tasks in CASA are python interfaces to the more basic toolkit. Tasks are executed to perform a single job, such as loading, plotting, flagging, calibrating, and imaging the data.

The parameters used and their defaults can be obtained by typing help(<taskname>) at the Python prompt, where <taskname> is the name of a given task. This command lists all parameters, a brief description of the parameter, the parameter default, and any options if there are limited allowed values for the parameter.

Experimental tasks and algorithms

Some tasks and algorithms in CASA are labelled as Experimental or Unverified. These tasks have not been fully commissioned and/or verified. Such tasks are provided to enhance user capabilities, or because they are required for specific pipeline use.

The label Experimental or Unverified means that the task/algorithm falls under the following disclaimers:

  • Only a subset of modes have been incorporated into CASA unit/regression tests. These are documented in CASA Docs. Other options/modes may be run, and might work just fine, but they are not part of what has been tested carefully.

  • Some parameters have been tested for specific use cases (as part of the algorithm development, publication, and CASA test programs), but we have not yet established best practices for all different situations. This information will build over time and will be incorporated into our documentation as appropriate.

  • Experimental tasks and algorithms may have Known Issues, representing CASA's current understanding of the state of the code. These Known Issues are clearly defined as part of CASA Docs.

  • Parameter names and task structure can change, based on feedback and improved understanding of usability.

It is expected that ALMA and VLA pipelines will begin using experimental tasks only after they have stabilized for stand-alone use.

The complete listing of tasks available in CASA is as follows:

Input / Output

exportasdm

Convert a CASA visibility file (MS) into an ALMA or EVLA Science Data Model

exportfits

Convert a CASA image to a FITS file

exportuvfits

Convert a CASA visibility data set to a UVFITS file:

importasdm

Convert an ALMA Science Data Model observation into a CASA visibility file (MS)

importatca

Import ATCA RPFITS file(s) to a measurement set

importfits

Convert an image FITS file into a CASA image

importfitsidi

Convert a FITS-IDI file to a CASA visibility data set

importgmrt

Convert a UVFITS file to a CASA visibility data set

importmiriad

Convert a Miriad visibility file into a CASA MeasurementSet

importuvfits

Convert a UVFITS file to a CASA visibility data set

importvla

Import VLA archive file(s) to a measurement set

splattotable

Convert a downloaded Splatalogue spectral line list to a casa table.

Information

asdmsummary

Summarized description of an ASDM dataset.

calstat

Displays statistical information on a calibration table

imhead

List, get and put image header parameters

imhistory

Retrieve and modify image history

imstat

Displays statistical information from an image or image region

listcal

List antenna gain solutions

listfits

List the HDU and typical data rows of a fits file:

listhistory

List the processing history of a dataset:

listobs

List the summary of a data set in the logger or in a file

listpartition

List the summary of a multi-MS data set in the logger or in a file

listsdm

Lists observation information present in an SDM directory.

listvis

List measurement set visibilities.

slsearch

Search a spectral line table.

vishead

List, summary, get, and put metadata in a measurement set

visstat

Displays statistical information from a MeasurementSet, or from a Multi-MS

Flagging

flagcmd

Flagging task based on batches of flag-commands

flagdata

All-purpose flagging task based on data-selections and flagging modes/algorithms.

flagmanager

Enable list, save, restore, delete and rename flag version files.

Calibration

accor

Normalize visibilities based on auto-correlations

applycal

Apply calibrations solutions(s) to data

bandpass

Calculates a bandpass calibration solution

blcal

Calculate a baseline-based calibration solution (gain or bandpass)

clearcal

Re-initializes the calibration for a visibility data set

fluxscale

Bootstrap the flux density scale from standard calibrators

fringefit

Fringe fit delay and rates

gaincal

Determine temporal gains from calibrator observations

gencal

Specify Calibration Values of Various Types

initweights

Initializes weight information in the MS

polcal

Determine instrumental polarization calibrations

polfromgain

Derive linear polarization from gain ratio

rerefant

Re-apply refant to a caltable

smoothcal

Smooth calibration solution(s) derived from one or more sources:

Imaging

apparentsens

Imaging sensitivity estimataion

deconvolve

Image-domain deconvolution

delmod

Deletes model representations in the MS

feather

Combine two images using their Fourier transforms

ft

Insert a source model as a visibility set

impbcor

Construct a primary beam corrected image from an image and a primary beam pattern.

makemask

Makes and manipulates image masks

predictcomp

Make a component list for a known calibrator

sdintimaging

Form images from interferometric visibilities and single dish image to reconstruct a sky model by joint deconvolution.

setjy

Fills the model column with the visibilities of a calibrator

tclean

Radio Interferometric Image Reconstruction

widebandpbcor

Wideband PB-correction on the output of the MS-MFS algorithm

Single Dish

importasap

Convert ASAP Scantable data into a CASA visibility file (MS)

importnro

Convert NOSTAR data into a CASA visibility file (MS)

nrobeamaverage

Average SD data over beams and do time averaging

sdatmcor

Offline correction of residual atmospheric features

sdbaseline

Fit/subtract a spectral baseline

sdcal

MS SD calibration task

sdfit

Fit a spectral line

sdfixscan

Task for single-dish image processing

sdgaincal

MS SD gain calibration task

sdimaging

SD task: imaging for total power and spectral data

sdpolaverage

Average SD spectra over polarisation

sdsidebandsplit

[EXPERIMENTAL] invoke sideband separation using FFT

sdsmooth

Smooth spectral data

sdtimeaverage

Average SD data, perform time averaging

tsdimaging

SD task: imaging for total power and spectral data

Manipulation

clearstat

Clear all autolock locks

concat

Concatenate several visibility data sets.

conjugatevis

Change the sign of the phases in all visibility columns.

cvel

regrid an MS to a new spectral window / channel structure or frame

cvel2

Regrid an MS or MMS to a new spectral window, channel structure or frame

fixplanets

Changes FIELD and SOURCE table entries based on user-provided direction or POINTING table, optionally fixes the UVW coordinates

fixvis

Recalculates (u, v, w) and/or changes Phase Center

hanningsmooth

Hanning smooth frequency channel data to remove Gibbs ringing

mstransform

Split the MS, combine/separate/regrid spws and do channel and time averaging

partition

Task to produce Multi-MSs using parallelism

phaseshift

Rotate a Measurement Set to a new phase-center

rmtables

Remove tables cleanly, use this instead of rm -rf

split

Create a visibility subset from an existing visibility set

statwt

Compute and set weights based on variance of data.

uvcontsub

continuum subtraction in the uv domain

uvcontsub_old

Continuum fitting and subtraction in the uv plane

uvmodelfit

Fit a single component source model to the uv data

uvsub

Subtract/add model from/to the corrected visibility data.

virtualconcat

Concatenate several visibility data sets into a multi-MS

Analysis

imbaseline

Image-based baseline subtraction for single-dish data

imcollapse

Collapse image along one axis, aggregating pixel values along that axis.

imcontsub

Estimates and subtracts continuum emission from an image cube

imdev

Create an image that can represent the statistical deviations of the input image.

imfit

Fit one or more elliptical Gaussian components on an image region(s)

immath

Perform math operations on images

immoments

Compute moments from an image

impv

Construct a position-velocity image by choosing two points in the direction plane.

imrebin

Rebin an image by the specified integer factors

imreframe

Change the frame in which the image reports its spectral values

imregrid

regrid an image onto a template image

imsmooth

Smooth an image or portion of an image

imsubimage

Create a (sub)image from a region of the image

imtrans

Reorder image axes

imval

Get the data value(s) and/or mask value in an image.

rmfit

Calculate rotation measure.

specfit

Fit 1-dimensional gaussians and/or polynomial models to an image or image region

specflux

Report spectral profile and calculate spectral flux over a user specified region

specsmooth

Smooth an image region in one dimension

spxfit

Fit a 1-dimensional model(s) to an image(s) or region for determination of spectral index.

Visualization

plotants

Plot the antenna distribution in the local reference frame:

plotbandpass

Makes detailed plots of Tsys and bandpass solutions.

plotprofilemap

Makes profile map.

plotweather

Plot elements of the weather table; estimate opacity.

Simulation

simalma

Simulation task for ALMA

simanalyze

image and analyze measurement sets created with simobserve

simobserve

visibility simulation task